The present invention pertains to a method and a device, as well as a sensor, for measuring a signal transmission channel from a transmitter to a sensor via a transmission path.
A transmission channel from a transmitter to a sensor needs to be determined in many fields of application. For example, it may be required to determine the distance of a reference object from other objects. In this case, for example, the amplitude attenuation of a light signal caused by the distance can be used in the form of 1/r4 for distance measurements.
In many known compensation methods, the actual transmission signal is superimposed with a compensation signal at the sensor in such a manner that the sensor in total receives a nearly constant signal. Examples include:
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DE10024156A1;
DE19839730C1;
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All these methods have the following common features:                the compensation signal and/or the transmission signal is an amplitude-controlled analog signal;        the transmission signal has a constant duty factor and/or is essentially monofrequent.        
The analog compensation signal is the significant disadvantage of all these methods. It requires an adjustable amplifier or, in other words, an analog multiplier that usually cannot be manufactured in a temperature-stable manner without substantial effort. Such a system is difficult to produce. It particularly requires very complex analog in-production inspections.